U.S. patent number 5,801,643 [Application Number 08/801,407] was granted by the patent office on 1998-09-01 for remote utility meter reading system.
This patent grant is currently assigned to Northrop Grumman Corporation. Invention is credited to Warren E. Guthrie, James Jensen, Thomas E. Szmurlo, Roger B. Williams.
United States Patent |
5,801,643 |
Williams , et al. |
September 1, 1998 |
Remote utility meter reading system
Abstract
In a method for transmitting a desired parameter to a remote
location, the desired parameter is first communicated to a base
transmitter. Then, the base transmitter transmits a first radio
signal therefrom having an unknown center frequency within a known
frequency band. The first radio signal comprises information
representative of the desired parameter. At a remote location, a
remote receiver identifies the center frequency of the first radio
signal and tunes the remote receiver to the center frequency
thereof so as to facilitate reception of the first radio signal
with the remote receiver. The information representative of the
desired parameter may then be communicated to a desired
destination.
Inventors: |
Williams; Roger B. (Lake
Zurich, IL), Szmurlo; Thomas E. (Palatine, IL), Guthrie;
Warren E. (Wheaton, IL), Jensen; James (Palatine,
IL) |
Assignee: |
Northrop Grumman Corporation
(Los Angeles, CA)
|
Family
ID: |
25181010 |
Appl.
No.: |
08/801,407 |
Filed: |
February 20, 1997 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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667896 |
Jun 20, 1996 |
|
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Current U.S.
Class: |
340/870.02;
370/320 |
Current CPC
Class: |
G06Q
10/087 (20130101); G06K 19/0716 (20130101); G08C
17/02 (20130101); G06K 7/10059 (20130101); H04Q
9/00 (20130101); G06K 17/0022 (20130101); G06K
7/10356 (20130101); G01R 22/00 (20130101); G01D
4/004 (20130101); G06K 7/0008 (20130101); Y04S
20/322 (20130101); H04Q 2209/60 (20130101); H04Q
2209/40 (20130101); Y02B 90/20 (20130101); Y02B
90/242 (20130101); Y04S 20/30 (20130101) |
Current International
Class: |
G06Q
10/00 (20060101); G08C 17/02 (20060101); H04Q
9/00 (20060101); G01D 4/00 (20060101); G08C
17/00 (20060101); G06K 7/00 (20060101); G08B
13/14 (20060101); G06K 17/00 (20060101); G08C
015/06 (); G08C 019/20 () |
Field of
Search: |
;340/870.02,870.18,870.26 ;375/206,200 ;455/71 ;370/320 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Horabik; Michael
Assistant Examiner: Edward, Jr.; Timothy
Attorney, Agent or Firm: Anderson; Terry J. Hoch, Jr.; Karl
J.
Parent Case Text
RELATED APPLICATIONS
This patent application is a continuation-in-part patent
application of U.S. Ser. No. 08/667,896, filed Jun. 20, 1996, and
entitled RANDOM INTERVAL INVENTORY SYSTEM.
Claims
What is claimed is:
1. A method for transmitting a desired parameter from a base
station to a remote location, the method comprising the steps
of:
a) transmitting a first radio signal via pulse position modulation
from the base transmitter to a relay transceiver disposed at a
location intermediated the base station and the remote
location;
b) receiving the first radio signal with the relay transceiver;
and
c) relaying the data via direct sequence spread spectrum modulation
from the relay transceiver to the remote location.
2. The method as recited in claim 1, further comprising the step of
transmitting a second radio signal from the remote location to the
base station, the second radio signal comprising instructions for
regulating operation of at least one device.
3. The method as recited in claim 1, wherein the step of
transmitting a first radio signal comprises transmitting a first
radio signal having a duration of less than approximately 100
milliseconds so as to mitigate communications contention.
4. The method as recited in claim 1, further comprising the steps
of:
a) compressing data representative of the desired parameter;
b) storing the compressed data; and
c) transmitting the compressed data to a desired location via
telephone at a time when telephone rates are favorable.
5. The method as recited in claim 1, wherein the step of
transmitting a first radio signal comprises transmitting a first
radio signal representative of a utility meter reading.
6. A system for transmitting a desired parameter from a base
station to a remote location, the system comprising:
a) a base transmitter disposed at the base station and configured
to transmit a first radio signal via pulse position modulation to a
relay transceiver disposed at a location intermediated the base
station and the remote location; and
b) a relay transceiver configured to receive the pulse position
modulated first radio signal and to relay the data via direct
sequence spread spectrum modulation from the relay transceiver to
the remote location.
7. The system as recited in claim 6, wherein the relay transmitter
is configured to transmit a second radio signal from the remote
location to the base station, the second radio signal comprising
instructions for regulating operation of at least one device.
8. The system as recited in claim 6, wherein the base transmitter
is configured to transmit a first radio signal having a duration of
less than approximately 100 milliseconds so as to mitigate
communications contention.
9. The system as recited in claim 6, further comprising:
a) a circuit for compressing data representative of the desired
parameter; and
b) a memory for storing the compressed data;
c) wherein compressing and storing the data facilitate subsequent
transmission of the compressed data to a desired location via
telephone at a time when telephone rates are favorable.
10. The system as recited in claim 6, wherein the base transmitter
is configured to transmit a first radio signal representative of a
utility meter reading.
Description
FIELD OF THE INVENTION
The present invention relates generally to utility meter reading
and more particularly to a system for transmitting a utility meter
reading or the like to a remote location, thereby mitigating the
prior art need to have a person individually read each separate
utility meter in a given neighborhood.
BACKGROUND OF THE INVENTION
Utility meters for providing an indication of the consumption of a
utility by a particular residence or business are well known. Such
utility meters allow a meter reader (a person responsible for
reading the utility meters) to visually observe an indication of
the amount of the utility consumed since the previous utility meter
reading. Such utility meters are commonly used by electric
companies, gas companies, and water companies.
As those skilled in the art will appreciate, the costs associated
with employing meter readers is substantial. In view of the
substantial costs associated with employing a person to manually
read utility meters, various attempts have been made in the prior
art to automate meter reading.
For example, U.S. Pat. No. 5,194,860 issued on Mar. 16, 1993 to
Jones et al., entitled RADIO TELEMETRY SYSTEMS WITH CHANNEL
SELECTION discloses a radio telemetry system for collecting the
readings of consumers' electricity meters. The system includes a
master station carried by a vehicle and a plurality of
transceivers, each of which stores an electrical quantity
indicative of the amount of electrical power consumed as measured
by the meter associated with that particular transceiver. The
transceivers and the master station communicate such that the
transceivers transmit to the master station signals containing
information as to the values of the electrical quantities stored
therein.
However, although the Jones et al. system does eliminate the need
for the meter reader to individually view each utility meter, it
still requires that the master station, which is carried by a
vehicle, be driven through the neighborhood, within the range of
each transceiver, so as to effect meter reading. Thus, although
Jones et al. does substantially simplify meter reading, it still
has the inherent disadvantage of requiring the employment of
personnel to effect meter reading.
Various attempts have also been made to transmit a signal
indicative of the meter reading to a central location. Such prior
art attempts have included an arrangement in which communication is
carried out using the power transmission line of the electric
utility. However, significant technical difficulties have been
encountered in attempting to communicate along the electrical power
line.
An attempt has also been made to utilize pre-existing telephone
lines for such communication. However, use of the telephone lines
provides a significant disadvantage since it relies heavily upon
other parties, e.g., the telephone company, for implementing the
system. Utility companies are apparently reluctant to use a system
which they cannot entirely control and manage themselves.
Another system, which utilizes radio communications, was developed
by Data Beam, which was a subsidiary of Connecticut Natural Gas.
According to this prior art system, a meter reading device is
mounted on the meter with a transmitting antenna which is separate
from the meter reading device. The transmitting antenna is located
on the building or other part of the installation site, thus
enabling the antenna to transmit over a relatively large distance.
The Data Beam system uses a number of receiving units, each
arranged to receive data from a large number of transmitters,
typically in the range of 10,000 to 30,000.
However, this arrangement results in the generation of a
significant number of installation problems, typically due to
wiring the antenna through the building to the transmitter and
receiver. Further, the anticipated high level of power use required
for transmitting is expected to involve either undesirably
expensive battery systems or undesirably expensive wiring.
Another system utilizing radio communications is disclosed in U.S.
Pat. No. 5,553,094 issued to Johnson et al. on Sep. 3, 1996 and
entitled RADIO COMMUNICATION NETWORK FOR REMOTE DATA GENERATING
STATIONS. Johnson et al. discloses a hierarchical network defining
a wide area communications system for communicating meter readings
to a central location.
One problem typically associated with such prior art radio
communication systems is that of the cost associated with providing
a large number of transmitters. As those skilled in the art will
appreciate, the cost of providing a large number of such
transmitters, particularly when such transmitters are constructed
so as to transmit the radio signals on a precise, predetermined
radio frequency, is substantial. Thus, it would be desirable to
provide a system which mitigates the need to have a person
individually read a large number of utility meters and which is not
prohibitively expensive to install and maintain. More particularly,
it would be beneficial to provide means for constructing such a
system wherein the cost of each transmitter is substantially
reduced, thereby dramatically decreasing the overall cost of the
system.
SUMMARY OF THE INVENTION
The present invention specifically addresses and alleviates the
above-mentioned deficiencies associated with the prior art. More
particularly, the present invention comprises a method and
apparatus for transmitting a desired parameter, e.g., a utility
meter reading, to a remote location such as a central billing
office. The system comprises a base transmitter to which the
utility meter reading is communicated and which is utilized for
transmitting a first radio signal therefrom. The first radio signal
has an unknown center frequency within a known frequency band and
comprises information representative of the utility meter
reading.
It is to be understood that the preferred embodiment of the present
invention comprises a system for transmitting utility meter
readings to a remote location. However, as those skilled in the art
will appreciate, various different desired parameters may similarly
be transmitted. For example, the temperature of a room, the
temperature of a freezer or oven, the level of liquid in a tank,
the status of a machine or computer, etc. may similarly be
transmitted. Thus, the use of utility meter reading herein is by
way of example only and not by way of limitation.
A remote receiver, positioned a distance away from the utility
meter and its associated base transmitter, is configured to
identify the center frequency of the first radio signal and to tune
to the center frequency of the first radio signal so as to
facilitate reception of the first radio signal. As those skilled in
the art will appreciate, various scanning devices are suitable for
scanning within a predetermined band or frequency range, so as to
determine the center frequency of a received signal.
An output circuit of the remote receiver communicates information
representative of the utility meter reading from the remote
receiver to a desired destination, such as a central billing
office.
According to the preferred embodiment of the present invention,
each of the base transmitters (one base transmitter being utilized
to transmit a meter reading from each meter) is constructed of low
cost components. This results in the output frequency of each base
transmitter drifting substantially, within a predetermined band or
range of frequencies, thus requiring the use of a scanner to
determine the center frequency of each radio signal being received.
However, because of the large number of individual base
transmitters utilized, it is cost effective to provide a single
scanner for each remote receiver, rather than constructing each
base transmitter with components having sufficient tolerances to
ensure stable transmission. Thus, each remote receiver compensates
for inadequate accuracy in the transmissions of the base
transmitters.
Thus, according to the preferred embodiment of the present
invention, each base transmitter comprises an oscillator which
drifts in frequency so as to provide a first radio signal having an
unknown signal frequency. The oscillator preferably drifts in
frequency so as to define a frequency band having a bandwidth of
approximately 1 MHz.
Further, according to the preferred embodiment of the present
invention, a timing circuit effects transmission of the first radio
signal at either a random interval or a pseudo-random interval, so
as to mitigate communications contention and so as to conserve
power. Communications contention is mitigated since the use of such
a random or pseudo-random transmission interval substantially
reduces the likelihood that two base transmitters will transmit to
a single remote receiver at the same instant. Indeed, if two base
transmitters were to transmit to the same remote receiver at the
same instant, both such transmissions would be ignored and it is
extremely unlikely that subsequent retransmissions of the two base
transmitters would occur at exactly the same instant again, since
the time intervals between transmissions are either random or
pseudo-random in nature.
The battery power of the base transmitter is conserved by utilizing
a random or pseudo-random transmission interval protocol, as
compared to a polling protocol, since when a random or
pseudo-random timing interval is utilized an associated receiver
does not have to be powered up and waiting to be polled. Thus,
substantial power is only utilized during the brief interval of
transmission.
The base transmitter preferably comprises a circuit for
transmitting a direct sequence spread spectrum radio signal. As
those skilled in the art will appreciate, it is possible to
maximize the effective range of such a transmitter, without
requiring FCC licensing, via the use of direct sequence spread
spectrum modulation.
Optionally, a remote transmitter is in electrical communication
with the base receiver and a remote receiver is in electrical
communication with the base transmitter. The remote transmitter
transmits a second radio signal to the base receiver. The second
radio signal comprises a verification that the first radio signal
has been properly received by the remote receiver and/or provides
instructions for regulating the operation of at least one device.
Such as the utility meter itself or a device serviced by the
utility metered thereby.
The use of such a verification signal (the second radio signal)
facilitates the immediate retransmission of the first radio signal
in the event that it was not properly received by the remote
receiver.
Thus, the present invention may optionally be utilized to regulate
the operation of one or more devices which consume the utility
being monitored by the utility meter. For example, during periods
of peak electrical power consumption, high consumption devices,
such as air conditioners, may be shut down or may be commanded to
operate at reduced capacity. Of course, the regulation of such
devices is typically more appropriate in industrial settings, where
the power consumption is generally substantially greater and
wherein operations, such as manufacturing activities, may
potentially be postponed.
The remote transmitter, as utilized, preferably transmits via pulse
position modulation (PPM). As used herein, the term pulse position
modulation is defined as the modulation of a radio signal which
comprises the transmission of a synch pulse followed by at least
one data pulse wherein the time interval between the synch pulse
and the data pulse(es) determines the character so transmitted. As
those skilled in the art will appreciate, pulse position modulation
tends to optimize range for a given average output power.
The use of pulse position modulation having a duty cycle of less
than one percent eliminates the requirement for FCC licensing by
maintaining a 50 mV/M measured at 10 meters output of less than
average. According to the preferred embodiment of the present
invention, the base transmitter is configured to transmit the first
radio signal using direct sequence spread spectrum (DSSS) at a
power of 30 dBm peak or less. Thus, PPM and DSSS provide adequate
range while not requiring FCC licensing.
The information representative of the utility meter reading may be
forwarded by the remote receiver by any one of a different number
of systems, as desired. For example, the remote receiver may
utilize the conventional telephone system, the cellular telephone
system, or a satellite communication system to relay meter readings
and the like to a central billing office. Control signals may
similarly be transmitted from the central billing office to the
remote transmitter, such that the control signals may be forwarded
to the appropriate devices associated with the base transmitter so
as to effect the regulation of a utility meter or device co-located
therewith.
Preferably, the first radio signal comprises an identification code
for the utility meter, so as to associate the meter reading
therewith. Optionally, the base transmitter further comprises a
circuit for providing information representative of the status of a
device, such as the utility meter, so as to facilitate control
thereof.
The remote receiver is preferably disposed upon a light pole,
utility pole, chimney, or other high structure, so as to facilitate
radio communication between the remote receiver and the plurality
of base transmitters.
According to the preferred embodiment of the present invention, the
base transmitter is configured to transmit the first radio signal
such that the first radio signal has a duration of less than
approximately 100 msec so as to mitigate the communications
contention. Further, the base transmitter is preferably configured
so as to transmit the first radio signal at a time which is
staggered, e.g., via the use of random or pseudo-random time
intervals as discussed above, relative to the times at which the
other radio signals from other transmitters are transmitted, so as
to further mitigate the communications contention.
Optionally, a data compression circuit in electrical communication
with the remote receiver compresses data representative of the
first radio signal and stores the compressed data. The compressed
data is then communicated to the desired destination at a time when
the telephone rates are favorable. The compressed data is then
decompressed at the desired destination, e.g., central billing
office, and utilized as desired.
Similarly, data may be compressed in the base transmitter prior to
transmission. The transmitter is optionally configured to transmit
the first radio signal on a more timely or near real time basis
such as approximately once per hour so as to facilitate more
precise monitoring of utility use. This data may be utilized to
effect control of the devices consuming the monitored utility in an
attempt to enhance the overall efficiency thereof or to mitigate
peak usage loads.
According to an alternative configuration of the present invention,
the base transmitter is battery powered and a relay transceiver
disposed at an intermediate location with respect to the base
transmitter and the remote receiver receives the first radio
transmission from the base transmitter and retransmits the data
from the first radio signal from the intermediate location to the
remote receiver. The relay transceiver is powered by an electrical
utility. Preferably, the relay transceiver is disposed proximate
the electric meter and utilizes electrical power received therefrom
to facilitate its operation thereof. As such, the use of such a
relay transceiver reduces the power drain placed upon the batteries
of one or more base transmitters which transmit therethrough,
thereby enhancing the battery life of the base transmitters.
When such a relay transceiver is utilized, each base transmitter
transmitting thereto is preferably configured to transmit a first
radio signal via pulse position modulation and the relay
transceiver is preferably configured to transmit the radio signal
from the intermediate location to the remote receiver via direct
sequence spread spectrum modulation.
The first radio signal is preferably transmitted from the base
transmitter to the relay transceiver via pulse position modulation
utilizing on-off keying. As those skilled in the art will
appreciate, a maximum average of -1 dBm effective radiated power is
permitted by the FCC when using on-off keying modulation in an
unlicensed band. Thus, each base transmitter may utilize up to -1
dBm effective radiated power to transmit the first radio signal to
its associated relay transceiver.
According to an alternative configuration of the present invention,
functions of the base transmitter and the relay transceiver are
combined such that a single enhanced base transmitter is provided
which receives information representative of a utility meter
reading, for example, and transmits that information to a remote
receiver. The enhanced base transmitter receives electrical power
from an electrical utility, as does the relay transceiver discussed
above, and therefore does not require batteries.
Such an enhanced base transmitter finds particular application in
industrial settings wherein large quantities of the monitored
utilities are typically consumed. In such industrial applications,
a receiver is preferably associated with the base transmitter so as
to receive control signals from a remote transmitter. Such control
signals may be utilized to control the activities of devices which
consume the monitored utility, so as to enhance the efficiency of
the utility distribution system and mitigate peak utility
consumption, particularly during those times when many users are
consuming that particular utility.
Thus, as discussed in detail above, information representative of
utility meter readings and the like is communicated either directly
from the base transmitter to the remote transmitter or,
alternatively, is communicated from the base transmitter to a relay
transceiver which does not rely upon battery power (as does the
associated base transmitter) and which then retransmits the
information to the remote receiver. These communications all
represent the transfer of data from the base transmitter to the
remote transmitter. However, as discussed briefly above, it is also
frequently desirable to transmit data from a remote location, e.g.,
a central billing office or the like, to the base transmitters
associated with the utility meters. Such reverse communication
would allow for individual control of the utility meter and also so
as to facilitate the performance of various different activities by
the base transmitter. For example, the base transmitter may be
instructed to transmit at different times, different time
intervals, or utilizing a different random or pseudo-random
algorithm. The utility meter may also be instructed to terminate
the utility for non-paying customers, for example.
A selectable IF (intermediate frequency) is utilized in the relay
transceiver to facilitate the reception of radio signals from
either the base transmitter or the remote transmitter. The IF
filter of the relay transceiver remains in a wideband mode of
operation while listening for a transmitted first radio signal from
a base transmitter. The bandwidth of the IF of the relay
transceiver is preferably approximately 2 MHz so as to accommodate
the known frequency band of +/-1 MHz of the base transmitters which
is due to oscillator drift. As mentioned above, the use of low-cost
oscillators in each of the base transmitters substantially reduces
the overall cost of the system, but results in the transmission of
a first radio signal having an unknown center frequency within a
known frequency band, e.g., of approximately +/-1 MHz. In order to
compensate for oscillator drift in the base transmitters, the relay
transceivers, which are substantially fewer in number, must be able
to receive signals within the wide bandwidth, e.g., approximately 2
MHz.
When the relay transceiver is listening for a radio transmission
from a remote transmitter, it is placed in a narrowband mode,
preferably having a bandwidth of approximately 30 kHz. Switching
the relay transceiver into the narrowband mode enhances the
sensitivity of its receiver by 18 dB, thus allowing it to receive
radio signals from remote transmitters at a substantially greater
distance than it is capable of receiving radio signals from base
transmitters. Of course, the larger the number of relay
transceivers that a given remote transmitter can transmit to, the
lower overall cost of the system. The local oscillators of both the
base transmitter and the relay transceiver are offset by the
intermediate frequency, which is common to both the base
transmitter and relay transceiver.
Alternatively, cellular data modems may be disposed right at each
utility meter itself, or proximate thereto. Each cellular data
modem will then transmit a signal representative of the meter
reading to the central billing office via the cellular telephone
system. Optionally, a single cellular data modem may be in
electrical communication with a plurality of different utility
meters, and thus may be utilized to transmit signals representative
of the plurality of utility meter readings.
As a further alternative, base transmitters for a plurality of
different utility meters may transmit to a local receiver, i.e.,
within a single house or a small group of houses, which then
utilizes a cellular data modem to transmit signals representative
of a plurality of utility meter readings to the central billing
office via the cellular network.
According to the present invention, a system is provided which
facilitates remote utility meter reading or the like and which
utilizes a large number of low-cost base transmitters for
transmitting information representative of the utility meter
reading while utilizing a much smaller number of more
sophisticated, more expensive remote receivers capable of receiving
the unstable transmission frequencies from the base
transmitters.
These, as well as other advantages of the present invention will be
more apparent from the following description and drawings. It is
understood that changes in the specific structure shown and
described may be made within the scope of the claims without
departing from the spirit of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of a neighborhood wherein each
house has a base transmitter associated with at least one utility
meter thereof for transmitting information representative of the
utility meter reading to a remote receiver disposed upon a utility
pole or the like which then communicates the utility meter reading
to a central billing office via a cellular telephone network;
FIG. 2 is a schematic representation of a base transmitter
associated with a utility meter which transmits a first radio
signal representative of the utility meter reading directly to a
remote receiver disposed upon a utility pole or the like;
FIG. 3 is a schematic representation of a neighborhood wherein two
relay transceivers are utilized to receive information
representative of utility meter readings from base transmitters and
to relay that information to a remote receiver;
FIG. 4 is a schematic representation of a base transmitter
associated with a utility meter which transmits a first radio
signal representative of the utility meter reading to a relay
transceiver, the relay transceiver then relaying the data to a
remote receive disposed upon a utility pole or the like;
FIG. 5 shows the schematic representation of FIG. 2 and includes
further detail of the base transmitter and remote receiver;
FIG. 6 shows the schematic representation of FIG. 4 and includes
further detail of the relay transceiver; and
FIG. 7 is a schematic representation of a single home having a
cellular data modem for receiving radio signals from at least one
base transmitter so as to transmit a utility meter reading thereof
to a central billing office via the cellular telephone network.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The detailed description set forth below in connection with the
appended drawings is intended as description of the presently
preferred embodiment of the invention and is not intended to
represent the only form in which the present invention may be
constructed or utilized. The description sets forth the functions
and the sequence of steps for constructing and operating the
invention in connection with the illustrated embodiment. It is to
be understood, however, that the same or equivalent functions and
sequences may be accomplished by different embodiments that are
also intended to be encompassed within the spirit and scope of the
invention.
The utility meter reading system of the present invention is
illustrated in FIGS. 1-7 which depict a presently preferred
embodiment thereof.
Referring now to FIGS. 1 and 2, the present invention generally
comprises a plurality of base transmitters 10, each base
transmitter 10 being associated with a utility meter 12.
Each base transmitter 10 is in communication with its associated
utility meter 12, preferably via direct electrical connection
thereto. Thus, each base transmitter 10 receives a signal
representative of the reading of the utility meter 12, such that it
may be transmitted therefrom as a first radio signal.
Optionally, a plurality of separate utility meters 12 may be
connected to a single transmitter base 10. Thus, in a typical
residence the electric, gas, and water meters may either each have
their own, individual base transmitters 10, or may alternative be
connected to a common base transmitter 10. As those skilled in the
art will appreciate, various combinations of dedicated and shared
base transmitters may be utilized, as desired.
Each base transmitter 10 is configured to transmit, preferably at
different times from one another, a first radio signal 22 to a
remote receiver 16 which is preferably disposed upon a utility
pole, light pole, tower, or other comparatively high structure 18
which facilitates the reception of the first radio signal 22 from
the base transmitters 10 in the neighborhood 20.
The remote receiver 16 is in electrical communication with a remote
transmitter 24 which is configured to transmit the information
representative of the utility meter reading to a desired
destination, such as a central billing office, preferably via a
cellular telephone signal 26 which is received by a cellular base
station 28. Those skilled in the art will appreciate that various
different methods for communicating the information contained in
the first radio signal from the remote receiver 16 to the central
billing office may be utilized. For example, hardwired telephone
lines, cellular telephone lines, satellite communication, etc. may
be utilized.
Thus, according to a first configuration of the present invention,
a utility meter reading or the like is transmitted from a base
transmitter 10 located in each home 14 to a remote receiver 16,
typically located within or close to the neighborhood, preferably
centrally located with respect thereto. The utility meter reading
is then relayed to the central billing office via the most
cost-effective means available.
In many instances it will be preferable to power the base
transmitter 10 via batteries, since many utility meters are not
located near an electrical power source, such as an electrical
outlet of the residence. Thus, in order to avoid the expense of
wiring the base transmitter 10 into the house's electrical wiring,
replaceable batteries may be utilized. However, since such
batteries must ultimately be removed and replaced, it is desirable
to maximize their life by minimizing power consumption by the base
transmitters 10. The power consumption of the base transmitters 10
is mitigated by the use of random or pseudo-random interval
transmission and by the use of direct sequence spread spectrum
modulation, as discussed in detail below.
Referring now to FIGS. 3 and 4, it will be appreciated that in some
instances excessive battery consumption would be required in order
to provide the power necessary to transmit from a base station 10
to the remote receiver 16. In such instances, it may be preferable
to provide a relay transceiver so as to facilitate operation of the
nearby base transmitters 10 within a desirable range of battery
power consumption. Each relay transceiver 32 is powered by an
electrical utility, i.e., house wiring, such that it does not
depend upon a battery for power. Thus, the use of such a relay
transceiver 32 further enhances the life of the batteries utilized
to power each base transmitter 10 which transmits to the relay
transceiver 32. Since each base transmitter 10 need only consume
enough power to transmit the comparatively short distance to the
relay transceiver 32, rather than the much longer distance to the
remote receiver 16.
When such relay transceivers 32 are utilized, then each base
transmitter 10 transmitting thereto is preferably configured to
transmit utilizing position pulse modulation, which is a form of
on-off keying. Thus, the radio signal 34 from the base transmitter
10 to the relay transceiver 32 preferably comprises a position
pulse modulated radio signal utilizing on-off keying and the radio
signal 22 from the relay transceiver 32 to the remote receiver 16
preferably comprises a direct sequence spread spectrum modulated
signal.
Referring now to FIG. 5, each base transmitter 10 preferably
comprises a data input port 40 which receives an electrical signal
representative of the utility meter reading and provides that
signal to a microprocessor 42. The microprocessor 42 encodes the
utility meter reading, as desired, and also facilitates
transmission thereof at a random or pseudo-random time interval.
Modulator 44 accepts the output of microprocessor 42, i.e., a
signal representative of the utility meter reading, and also
accepts the output of the local oscillator 46 to effect modulation
thereof. Power amplifier 48 boosts the output power of the radio
frequency signal prior to its being transmitted via antenna 50.
Bandpass filter 49 defines the broadcast bandwidth of the first
radio signal 22.
Antenna 50 may likewise be utilized to receive a second radio
signal, transmitted by a remote transmitter 52 which is filtered by
bandpass filter 53 amplified via amplifier 54 and converted to an
IF frequency via mixer 56, filtered by bandpass filter 57, and then
provided to microprocessor 42 via demodulator 58. In an alternate
embodiment, a separate receive and transmit antenna may be
utilized. The data output from output 60 may then be utilized by
the microprocessor 42 to effect control of the utility meter 12
and/or a device which is monitored thereby. A control signal may be
utilized to change the length of the time interval at which utility
meter reading are taken or to cause the utility meter 12 to shut
down the utility being provided, as discussed above. Further, the
data output signal may be utilized to modify operation of the
monitored device, so as to reduce consumption of the monitored
utility during peak usage, for example. The signal provided from
the data output port 60 may also comprise a verification signal for
effecting re-transmission of the utility meter reading when it has
not been properly received by the remote receiver 16.
The remote receiver 16 and transmitter 52, preferably comprises an
oscillator 64 which provides an output to both the direct sequence
spread spectrum remote receiver 16 and the on-off key remote
transmitter 52, both of which utilize antenna 66. The on-off key
remote transmitter 52 facilitates the transmission of the second
radio signal 68 therefrom to the base receiver 70.
Referring now to FIG. 6, the optional relay transceiver 32
preferably comprises an antenna 80 for both receiving and sending
radio signals. An alternate embodiment uses separate receive and
transmit antenna. Bandpass filter 81 passes frequencies within the
bandwidth, typically several megaHertz, where the signal from the
base transmitters 10 is located. Amplifier 82 amplifies the
filtered radio frequency signal and mixer 84 converts the radio
frequency signal to baseband. 1 MHz bandpass filter 86 provides
broadband reception of the radio signal from the base transmitter
10, while narrowband filter 88 facilitates reception thereof after
and the demodulator 90 provides the data output from output port 92
to the microprocessor 96. Data to be re-transmitted, such as that
from data input port 94, is provided to the microprocessor 96. In
the preferred embodiment, the relay transceiver switches the local
oscillator 85 frequency to a different frequency when in wide or
narrowband reception. Microprocessor 96 encodes the data, as
desired, and facilitates transmission thereof at a desired time.
The data to be transmitted is output from microprocessor 96 through
modulator 98, which utilizes local oscillator 85, to power
amplifier 100. Bandpass filter 102 provides a signal of the desired
frequency content to antenna 80.
According to the preferred embodiment of the present invention,
each remote transmitter and receiver service a neighborhood having
a radius of approximately one mile, thus covering approximately six
square miles.
According to the preferred embodiment of the present invention, the
on-off keying utilized to transmit from the base transmitter to the
relay transceiver comprises a 2,408.3 MHz radio signal. This is
received by the relay transceiver when the relay transceiver is in
the wideband mode. The relay transceiver's local oscillator is
preferably a 2,419 MHz oscillator which mixes the 2,408.3 signal
down to the relay transceiver's IF at 10.7 MHz.
The relay transceiver receives the on-off key modulated radio
signal from the base transmitter and relays it to the remote
receiver using direct sequence spread spectrum modulation at 2,414
MHz. Prior to performing the transmission to the remote receiver,
the relay transceiver switches to its narrowband IF filter.
The remote receiver receives the spread spectrum signal,
demodulates it, and determines the center frequency of the
transmission from the relay transceiver (or the base transmitter if
no relay transceiver is utilized).
After determining the center frequency of the radio transmission
from the relay transceiver 32, the remote receiver 16 adjusts for
frequency drift thereof and can then transmit back to the relay
transceiver 32 utilizing on-off key transmission at the correct
frequency so that the transmission from the remote transmitter 24
to the relay transceiver can be properly received, i.e., its
converted RF center frequency is within the relay transceiver IF
bandwidth when the relay transceiver 32 is utilizing the narrowband
filter thereof.
After receiving a radio transmission from the remote transmitter,
the relay transceiver switches from direct or spread spectrum
modulation to on-off key modulation and transmits to the base
receiver at 2,413.545 MHz. The local receiver receives the
2,413.545 MHz signal and uses its 2,414 MHz local oscillator to mix
the received radio signal down to 455 KHz IF for demodulation
thereof.
When a relay transceiver 32 is utilized, then the circuitry of the
base transmitter 10 is modified so as to accommodate the use of
pulse position modulation utilizing on/off key transmission, rather
than direct sequence spread spectrum modulation. Thus, as shown in
FIG. 6, the microprocessor 42 provides its output directly to
amplifier 48 where it controls passage of the oscillator signal 46
to the bandpass filter 49, thus effecting on/off keying.
Referring now to FIG. 7, according to a further alternative
configuration, the base transmitter 10 associated with each utility
meter 12 of a residence, for example, transmits a radio signal
representative of the meter reading to a receiver located within or
near the house 14 which is interfaced to a cellular data modem 110
via telephone interface 112. The cellular data modem 110 then
transmits the meter reading to the central billing office via the
cellular system.
It is understood that the exemplary remote utility meter reading
system described herein and shown in the drawings represents only a
presently preferred embodiment thereof. Indeed, various
modifications and additions may be made to such embodiment without
departing from the spirit and scope of the invention. For example,
those skilled in the art will appreciate various different
protocols and modulation methods are suitable for the transmission
of data between the base transmitter, relay transceiver, and the
remote receiver. Also, various different parameters, other than
utility meter readings, may be so transmitted. Thus, these and
other modifications and additions may be obvious to those skilled
in the art and may be implemented to adapt the present invention
for use in a variety of different applications.
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